With development of the telephone communication network, it has always been an important problem drawing attention of those skilled in the art how to effectively prevent surge overvoltage caused by lightning strike, AC power supply fluctuation or electromagnetic induction from destroying the communication equipment. After all the Euramerican countries issued an communication equipment anti-lightning and anti-surge standard of their own, our country also issued in 1998 the Communication Business Standard YD/T9931998 of the People's Republic of China—Technical Requirement and Experimental Method of Telecommunications Terminal Equipment against Lightning Strike. Within as short as several tens of years, the anti-surge protection device successively took the forms of a gas discharge tube, a TVS diode, a semiconductor solid discharge tube and a programmable protection device of transient voltage suppressor.
Fang ZHANG and Qiuping S U published a paper entitled “a protect device of programmable semiconductor surge suppressor” in Modern Electronic Technique 9 (200), 2005. This paper introduced circuit structure (as shown in FIG. 1) and operating principle of a fourth-generation programmable anti-surge protection device P61089, and analyzed mechanism of the device protecting the Subscriber Line Interface Circuit (SLIC) board on the program-controlled switchboard. The research showed that P61089 is a two-way bi-directional semiconductor anti-surge protection device, also based on the PNPN structure and principle, whose performance is also greatly improved better than the semiconductor anti-surge protection devices of the prior three generations; and meanwhile the device is further provided with a forward protection diode for clamping a forward surge and a gate-controlled triode for triggering, which thus allows hardware programming on the protective voltage (the programming range is −10˜−75 V to earth). P61089 is currently used in almost all of the program-controlled switchboards for protecting the SLIC board. However, lightning strike and surge still do damage to the telephone communication equipment, which puts forward higher requirements on anti-lightning performance of the semiconductor anti-surge protection device. The current programmable anti-surge protection device P61089 can only reach around 2000 V according to an anti-lightning performance test. Therefore, it is the problem the present invention studies how to improve the anti-lightning and anti-surge performance and the energy discharge capability of the current protection device of programmable semiconductor surge suppressor.